Pfizer presents overall survival data from PALOMA-3 trial of Ibrance
Pfizer announced detailed overall survival data from the PALOMA-3 trial, which evaluated Ibrance in combination with fulvestrant compared to placebo plus fulvestrant in women with hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer whose disease progressed on or after prior endocrine therapy. In the study, there was a numerical improvement in OS of nearly seven months with Ibranceplus fulvestrant compared to placebo plus fulvestrant, although this difference did not reach the prespecified threshold for statistical significance versus 28.0 months. The difference in median OS demonstrated in this analysis is consistent with the improvement previously demonstrated for the primary endpoint of median progression-free survival. In the updated PFS analysis for this study, the combination of Ibrance plus fulvestrant showed a statistically significant and clinically meaningful 6.6-month mPFS improvement compared to placebo plus fulvestrant. Overall survival is a secondary endpoint of PALOMA-3, and the trial design was not optimized to detect a statistically significant difference in OS. At the time of this analysis, follow-up was 44.8 months and approximately 60% of events had occurred in the 521 patients enrolled. Patients on both arms received up to 10 lines of post-progression treatment. The trend toward OS favoring the Ibrance plus fulvestrant arm was observed across most subgroups, with hazard ratios consistent with the overall population. In addition, for the overall population, the difference in OS was associated with prolonged time from randomization to first use of chemotherapy post-progression, an exploratory endpoint. Median time to chemotherapy was 17.6 months for patients who received Ibrance plus fulvestrant, twice that observed in patients who received placebo plus fulvestrant. The most common adverse reactions in PALOMA-3 included neutropenia, leukopenia, infections, fatigue and nausea. No new safety signals observed with longer follow-up were identified as part of this final OS analysis.